Abstract: Consecutive field investigations and observations were carried out over the Tibetan Plateau from 2014 to 2016 in order to obtain the temporal and spatial distribution of carbon in water from typical high-altitude rivers and lakes. Water from typical rivers, lakes and ice points were sampled to be analyzed using the vario TOC analyzer from German Elementar corporation in our laboratory. The total carbon concentration, total inorganic carbon concentration and total dissolved organic carbon concentration were obtained. Preliminary results show that inorganic carbon is the major form whereas organic carbon is the auxiliary form of carbon in water from typical rivers and lakes in the Tibetan Plateau and source region of three rivers, namely the Changjiang River, the Yellow River, and the Lancang River. The averaged concentration of total carbon in water from typical rivers and lakes over the source region of Changjiang River, Yellow River and Lancang River source area was 62.46 mg/L, 32.88 mg/L, and 17.70 mg/L, respectively; while the total carbon concentration in the Dangqu River source (southern source), the Tuotuo River source (main source) and the Qumar River (northern source) was 32.90 mg/L, 36.56 mg/L, and 32.90 mg/L, respectively. Over the Tibetan Plateau, the total carbon concentration and total inorganic carbon concentration in surface water from typical lakes (403.82 mg/L and 398.35 mg/L, respectively) were much higher than those from typical rivers (17.03 mg/L and 14.56 mg/L, respectively); however, total organic carbon concentration displayed an opposite trend, with 1.24 mg/L in lakes and 2.46 mg/L in rivers. The research results are of vital importance for the climate change and water resources and eco-environmental safety in the Tibetan Plateau and the source region of the three rivers.

Key words: carbon concentration in surface water, temporal and spatial changes, Tibetan Plateau, rivers and lakes, source of Three Rivers